This invention pertains to rotary compressors for compressing refrigerant in refrigeration systems such as air conditioners, refrigerators, and the like. In particular, the invention relates to discharge gas routing systems for such compressors to reduce noise pulsations and to provide cooler discharge gas.
In general, prior art hermetic rotary compressors comprise a housing which is hermetically sealed. Located in the housing are an electric motor and a compressor mechanism. The electric motor is connected to a crankshaft which has an eccentric portion thereon. The eccentric portion of the crankshaft is located within a compression chamber bore of the compressor cylinder block. A roller located within the compression chamber is mounted on the eccentric portion of the crankshaft and is driven thereby. The roller cooperates with a sliding vane to compress refrigerant within the bore of the cylinder block.
Rotary hermetic compressors of the type herein disclosed generally have a pressurized or high side sealed housing. Compressed gas from within the compression chamber is discharged through a gas routing system into the compressor housing. This discharge gas exhibits undesirable properties with respect to achieving quiet and efficient operation of the compressor. Specifically, noise pulsations are ordinarily caused by the discharge gas due to opening and closing of valving in response to the cyclical compression and suction created in the compression chamber within the cylinder block. Under certain operating conditions, and particularly for higher capacity compressors, these noise pulsations become objectionable to the consumer. Another problem associated with rotary hermetic compressors, wherein pressurized gas is discharged into the sealed housing, is a hot operating environment which tends to decrease the efficiency of the electric motor. High operating temperatures also result in undesirable high temperatures for the lubricating oil, the housing, and the discharge gas.
Prior art gas routing systems for rotary compressors have generally addressed the problem of excessive noise pulsations by providing a single discharge port in either of the main or outboard bearings through which compressed gas is removed from the compression chamber into a muffler or a series of mufflers. In several prior art gas routing systems, after the compressed gas is discharged through a bearing into a muffler cavity, it is rerouted through passageways extending through both bearings and the cylinder block and then through an auxiliary muffler system or directly into the housing.
Another prior art gas routing system provides for multiple discharge ports in the sidewall of the cylindrical compression chamber providing communication between the compression chamber and a discharge chamber defined within the cylinder block. From the discharge chamber, discharge gas passes through a single port extending through a bearing into a muffler before being discharged into the interior of the compressor housing. By providing a plurality of discharge ports in the sidewall of the compression chamber, cooler gas is discharged into the discharge chamber defined within the cylinder block. The gas is then recompressed and discharged through a single smaller opening in one of the bearings.
A disadvantage of the prior art solutions wherein compressed gas is discharged through a single opening in one of the main or outboard bearings is that a single opening in a rotary compressor cannot be made large enough to sufficiently reduce the level of noise pulsations. Furthermore, the temperature of gas discharged through a limited size opening is hotter than can otherwise be achieved though larger openings, thus increasing operating temperatures of the compressor and reducing compressor efficiency.
The prior art rotary compressor design utilizing a plurality of discharge ports in the sidewall of the cylinder provides a baffling chamber in the cylinder block. However, the discharge gas is ultimately discharged through one port in one of the bearings into a single muffler, thereby maintaining objectionable sound pulsations. A further problem with a rotary compressor having a discharge chamber defined within the cylinder block is that compressor size may be increased by the need for space surrounding the compression chamber. Also, heat generated in the compression chamber and dissipated into the cylinder block maintains the discharge gas within the discharge chamber at higher temperatures, thereby decreasing its ability to cool compressor components when discharged within the housing.
It is also known in the art to provide a discharge muffler mounted on the outboard bearing in fluid communication with oil in the oil sump for the purpose of providing sound muffling. To this end, discharge gas may be discharged into the oil to cause cavitation and adherance of air bubbles to the discharge muffler for further sound muffling.